SHIFT DEVICE WITH SYNCHRONIZER ADAPTED FOR TRANSMISSION

Description

[0001] The present invention relates to a shift device with a synchronizer adapted for a transmission in which pushing force applied to a sleeve can be amplified into larger pushing force acting on a synchronizer ring while gears of the transmission are shifted, thereby reducing operating force required by a driver or an actuator.

[0002] A shift device with a synchronizer adapted for a transmission of this kind is disclosed in Japanese Examined Patent Application Publication No. 45-35684 US-A-3548983. This conventional shift device includes a hub and a sleeve, where the sleeve is formed with a slanted surface so that the slanted surface thereof can change a part of friction torque caused between the sleeve and the hub into thrust acting on the synchronizer ring, thereby increasing synchronizing ability. It may add a thrust plate which has slanted surfaces and is arranged between the sleeve and the hub.

[0003] This conventional shift device with the synchronizer, however, encounters the following problems.

[0004] The slant surface of the hub needs to be formed on the vicinity of a central portion in an axial direction thereof, which requires a difficult manufacturing process for forming the slant surface on the hub, consequently increasing its manufacturing costs.

[0005] It is, therefore, an object of the present invention to provide a shift device with a synchronizer adapted for a transmission which overcomes the foregoing drawbacks and can decrease manufacturing costs of a hub, keeping high synchronizing ability due to self-servo operation.

[0006] According to the present invention there is provided a shift device with a synchronizer which is adapted for a transmission as defined by claim 1.

[0007] Preferred embodiments of the invention are defined by the claims 2 to 5.

[0008] The objects, features and advantages of the present invention will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional plan view, taken along the line Z-Z in FIG. 2, showing a shift device with synchronizers of a first embodiment according to the present invention, the shift device being used for third speed and fourth speed;

FIG. 2 is a front view showing a hub, a sleeve, a synchronizer ring and three thrust pieces pushed by a spring outwardly in a radial direction of the shift device, which are used in the shift device of the embodiment shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional plan view showing a main part of the shift device shown in FIG. 1;

FIG. 4 is an enlarged fragmentary front view showing the hub of the shift device shown in FIG. 1;

FIG. 5 is a development-elevated fragmentary view showing an outer peripheral part of the hub shown in FIG. 4, seen from the outside of the hub in the radial direction;

FIG. 6 is an enlarged fragmentary front view showing the sleeve used in the select device shown in FIG. 1;

FIG. 7 is a cross-sectional view, taken along the line Z-Z in FIG. 2, showing the synchronizing ring;

FIG. 8 is an enlarged fragmentary front view showing the synchronizer ring;

FIG. 9 is an enlarged fragmentary cross-sectional view of the synchronizer ring shown in FIGS. 7 and 8;

FIG. 10 is a development-elevated view showing the synchronizer ring, seen from the outside of the hub in the radial direction;

FIG. 11 is an enlarged cross-sectional view showing a thrust piece used in the shift device shown in FIGS. 1 and 2;

FIG. 12 is a development-elevated view showing the thrust piece shown in FIG. 11, seen from the outside of the hub in the radial direction;

FIG. 13 is a front view showing the thrust piece shown in FIGS. 11 and 12;

FIG. 14 is a development elevation showing a state of the shift device when it is kept at a neutral position;

FIG. 15 is a development elevation showing a position relationship between the thrust piece and the synchronizer rings sandwiching the thrust piece;

FIG. 16 is a development elevation showing a state of the shift device when the sleeve is moved toward the third gear and a first slant surface of the thrust piece, pressed by a chamfer surface of the synchronizer ring, contacts with a slant surface of the hub;

FIG. 17 is a cross-sectional plan view showing the state of the shift device shown in FIG. 16;

FIG. 18 is a development elevation showing a state of the shift device when the sleeve is further moved toward the third gear and the first surface of the thrust piece moves over the chamfer surface of the synchronizer ring;

FIG. 19 is a cross-sectional view showing the state of the shift device shown in FIG. 8; and

FIG. 20 is a cross-sectional plan view showing the main part of the shift device when the gear shifting toward the third speed is finished

Throughout the following detailed description, similar reference characters and numbers refer to similar elements in all figures of the drawings, and their descriptions are omitted for eliminating duplication.

[0009] Referring to FIGS. 1 to 3 of the drawings, there is shown a shift device, which has a synchronizer and is adapted for a transmission of a motor vehicle, of a first preferred embodiment according to the present invention.

[0010] The shift device includes an input shaft 10 connectable with a not-shown crank shaft of an engine via a not-shown clutch, a third gear 18, a fourth gear 20, and a synchronizer 2 placed between the third gear 18 and the fourth gear 20. The input shaft 10 is capable of transmitting drive power and acts as a shaft of the present invention. The third gear 18 and the fourth gear 20 act as a pair of speed gears of the present invention.

[0011] The input shaft 10 is formed on its partial outer surface with splines 10a, which is engaged by splines 12a formed on an inner surface of cylindrical boss portion 12b of a hub 12, so that the input shaft 10 drives the hub 12 to rotate together with each other at the same speed. The hub 12 is fixed to the input shaft 10 by contacting at its one side portion with a large diameter portion of the input shaft 10 and also contacting at its other end portion with a bush 14, which is press-fitted onto an outer surface of a small diameter portion of the input shaft 10.

[0012] The hub 12 has the boss portion 12b, a ring portion 12d arranged in coaxial with the boss portion 12b and outwardly in its radial direction, and a flange portion 12c connecting the boss portion 12b and the ring portion 12d and formed thinner in thickness than the boss portion 12b. Splines 12e are formed on the outer surface of the ring portion 12d and engage with splines 22a formed on an inner surface of a sleeve 22 so as to slide relative to each other in the axial direction.

[0013] The sleeve 22 is formed with a circumferential groove 22b on its outer surface, in which a not-shown shift fork is partially inserted. The shift fork is capable of moving in the axial direction according to a not-shown shift lever operated by a driver or a not-shown actuator.

[0014] On the input shaft 10, the third gear 18 is freely rotatably supported through a bearing 16a at one side of the hub 12, and the fourth gear 20 is freely rotatably supported though a bearing 16b at the other side of the hub 12. The third gear 18 and the fourth gear 20 are in constant mesh with not-shown gears on an output shaft arranged in parallel to the input shaft 10, respectively.

[0015] As shown in FIG. 3, the third gear 18 is formed to integrally have splines 18a and an outer conical friction surface 18b at the hub 12 side thereof. The splines 18a are capable of engaging with the spline 22a of the sleeve 22 by moving the sleeve 22 to a third speed position. The outer conical friction surface 18b faces to an inner conical friction surface 24a of a synchronizer ring 24. The inner conical friction surface 24a corresponds to a friction surface of the present invention.

[0016] Similarly, the fourth gear 20 is formed to integrally have splines 20a and an outer conical friction surface 20b at the hub 12 side thereof. The splines 20a are capable of engaging with the spline 22a of the sleeve 22 by moving the sleeve 22 to a fourth speed position. The outer conical friction surface 18b faces to an inner conical friction surface 24a of another synchronizer ring 24, which is arranged in symmetric with the synchronizer ring 24 at the third gear 18 side. The inner conical friction surface 24a corresponds to a friction surface of the present invention.

[0017] The sleeve 22 is designed to have lengths and positional relationships with other parts so as to move to be shiftable among the third speed position, the fourth speed position, and a neutral position. The neutral position is between the third and fourth speed positions as shown in FIGS. 1 and 3, where the splines 22a of the sleeve 22 are not in mesh with the splines 18a and 20a of the third and fourth gears 18 and 20. Note that the splines 22a of the sleeve 22 are in constant mesh with the splines 12e of the ring portion 12d at the third speed, neutral and fourth speed positions.

[0018] The synchronizer ring 24, the sleeve 22 and the splines 18a and 20a and the outer friction surfaces 18b and 20b of the third and fourth gears 18 and 20 constitute the synchronizer of the shift device.

[0019] The above-constructed synchronizer 2 of the embodiment further has a force amplifying mechanism, which is constructed as below.

[0020] A shown in FIG. 4, the flange portion 12c and the ring portion 12d of the hub 12 are partially cut off at three portions to form three notch portions 12f, in each of which a thrust piece 26 is located as shown in FIGS. 1 to 3. The thrust pieces 26 are also located between the synchronizer rings 24 and 24 in the axial direction, and between the hub 12 and the sleeve 22 in the radial direction. The thrust pieces 26 are pushed outwardly in a radial direction by three springs 28, which are arranged in an inner space formed by the three thrust pieces 26.

[0021] The notch portions 12f of the hub 12 are formed at four edges in the axial direction to have slanted surfaces 12g to 12j as shown in FIG. 5. These slanted surfaces 12g to 12j are designed to have a configuration to change directions of forces so that the thrust pieces 26 are pressed in the direction when the thrust pieces 26 contact with the slanted surfaces 12g to 12j of the hub 12 and rotating force is applied to the thrust pieces 26. The notch portions 12f are also formed at the boss portion 12b side with a seat surface 12k for receiving the spring 28.

[0022] As shown in FIG. 6, the splines 22a of the sleeve 22 are formed to have chamfers 22c and 22d at their axial both ends, three splines at three positions around a circumstance of the splines 22a of the sleeve 22 are formed inside thereof with projections 22g respectively having slanted surfaces 22e and 22f at both axial end portions of projections 22g. The projections 22g are engageable with the thrust piece 26. One spline , namely an intermediate one, of the three splines is has a projecting portion 22h at its axial central portion. The projections 22g are shorther in axial length than the splines, and the projecting portion 22h is shorter in the axial length than the projections 22g as shown in FIG. 3.

[0023] As shown in FIGS. 7 to 10, each synchronizer ring 24 is formed on its inner peripheral surface with a conical friction surface 24a. The conical friction surfaces 24a of the synchronizer rings 24 are arranged so as to face the friction surfaces 18b and 20b of the third and fourth speed gears, respectively.

[0024] The synchronizer rings 24 are also formed on its outer peripheral surface with three notch portions 24b, each of which has first end surfaces 24e and 24f, second end surfaces 24g and 24h and chamfers 24c and 24d connecting the first and second end surfaces 24e and 24g, 24f and 24h, respectively. At an intermediate and speed-gear side position in the notch portion 24b, a projection 24i is formed to have slanted surfaces 24j and 24k. The synchronizer ring 24 has a rear surface 241 at its hub 12 side.

[0025] As shown in FIGS. 11 to 13, the thrust pieces 26 are formed on its outer peripheral surfaces with a recess portion 26d having engageable slanted surfaces 26b and 26c, where a through-hole 26e at the center of the recess portion 26d is provided to connect with conical hole portion 26f. The conical hole portion 26f receives a ball 30 pressed by the spring 28.

[0026] The recess portion 26d corresponds to the projection 22g of the sleeve 22, and is designed so that the projecting portion 22h of the sleeve 22 can be received in the through-hole 26e of the thrust pieces 26 when the thrust piece 26 is engaged with the projection 22g as shown in FIGS. 1 to 3.

[0027] The thrust pieces 26 are formed to have an entirely curved portion as shown in FIG. 13, and are preferably formed as a part of a spherical shape.
They have shapes like a rectangle, seen from an upper side (from an outer side in the radial direction), having four projections 26g to 26j at its corners. The projections 26g to 26j are formed with first slanted surfaces 26k to 26n at the outer side in the axial direction and with second slanted surfaces 26o to 26r at the inner side in the axial direction, respectively. The first slanted surfaces 26k to 26n correspond to the chamfers 24c and 24d of the synchronizer ring 24, and the second slanted surfaces 26o to 26r correspond to the slanted surfaces 12g to 12j, respectively, so that the corresponding surfaces thereof are contactable with each other.

[0028] The thrust piece 26 is slightly swingable with respect to the hub 12, and accordingly the first slanted surfaces 26k to 26n and the second slanted surfaces 26o to 26r are formed to have a slightly circular arc surface with small rounded corners.

[0029] As shown in FIGS. 11 and 13, two recesses 26t are provided at both axial end portions on an inner peripheral surface 26s of the thrust piece 26, so as to correspond to the projection 24i of the synchronizer ring 24. Specifically, the projection 24i of the synchronizer ring 24 is received in one of the recesses 26t when the thrust piece 26 is moved inwardly in the radial direction.

[0030] The operation of the shift device of the embodiment will be described with reference to the drawings of FIGS. 3, 14 to 18. Note that the drawings of FIGS. 14 to 17 are development elevations for easy understanding.

[0031] At the neutral position, the sleeve 22 is positioned at a position shown in FIGS. 3 and 14, so that its splines 22a engage only with the splines 12e of the hub 12, not with the splines 24b of the synchronizer rings 24. In this position, the thrust pieces 26 are pushed outwardly in the radial direction by the springs 28, so that the thrust pieces 26 are engaged with the projections 22g of the sleeve 22 and the cut-off portions 12f of the hub 12. At this neutral position, the second slanted surfaces 26o to 26r of the thrust pieces 26 are not in contact with the slanted surfaces 12g to 12j of the hub 12.

[0032] As shown in FIG. 15, there are clearances X between the projections 26g to 26j of the thrust pieces 26 and the second end surfaces 24g and 24h of the synchronizer ring 24 at the neutral position. In other words, at the neutral position, there is a play, corresponding to the clearance X, in a rotational direction between the synchronizer ring 24 and the thrust pieces 26.

[0033] In order to obtain third speed, the sleeve 22 is moved toward the third gear 18. The sleeve 22 and the thrust pieces 26, engaged with the sleeve 22, move together, so that, first, the ball 30 contacts with the rear surface 241 of the synchronizer ring 24, pressing the synchronizer ring 24 toward the third gear 18 with force corresponding to tension of the springs 28. In this state, when there is a rotational speed difference between the input shaft 10 and the third gear 18, friction is generated between the friction surface 24a of the synchronizer ring 24 and the friction surface 18b of the third gear 18. The frictional torque generated therebetween rotates the synchronizer ring 24 with respect to the thrust pieces 26, thereby changing its state into a state shown in FIG. 16. In this state, the chamfers 24d of the synchronizer ring 24 contact with the first slanted surface 26l of the thrust pieces 26.

[0034] The thrust pieces 26 are slightly moved toward the third gear 18, so that they are swingable in the notch portions 12f of the hub 12. Consequently, the thrust pieces 26 are pressed by the chamfers 24d of the synchronizer ring 24 to be slightly swung in a clockwise direction as shown in FIG. 16, and the second slanted surfaces 26o of the thrust pieces 26 contact with the slanted surfaces 12i of the hub 12. The projections 24i are somewhat out of the recesses 26t of the thrust pieces 26 as shown in FIG. 16 . This causes the inner peripheral surfaces 26s of the thrust pieces 26 to contact with the slanted surfaces 24j of the projections 24i of the synchronizer ring 24, and accordingly the thrust pieces 26 can not move inwardly in the radial direction from a state shown in FIG. 17 corresponding to the state of FIG. 16. This maintains a state where the slanted surfaces 22e of the sleeve 22 and the engageable slanted surfaces 26b of the thrust pieces 26, so that the sleeve 22 keeps pressing the thrust pieces 26 in the axial direction.

[0035] On the other hand, the second slanted surfaces 260 of the thrust pieces 26 contact with the slanted surfaces 12i of the hub 12, and accordingly the friction torque transmitted through the chamfers 24c of the synchronizer ring 24 acts on the hub 12 through the thrust pieces 26. The second slanted surfaces 26o and the slanted surfaces 12i are capable of changing rotational force due to friction torque to thrust, when the friction torque generated by the rotational speed difference between the synchronizer ring 24 and the third gear 18 acts on the slanted surfaces 26o and 24d. Thus, thrust pieces 26 are pressed toward the third gear 18.

[0036] That is, when the friction torque Tf is generated in the state shown in FIGS. 16 and 17, the thrust pieces 26 applies axial resultant force Fm + Ft on the chamfers 24c of the synchronizer ring 24, where Fm is thrust pressed by the slanted surfaces 22e of the sleeve 22 and Ft is thrust generated by the first slanted surfaces 26k of the thrust pieces 26 and the slanted surfaces 12g of the hub 12. The thrust Ft acts as self-servo force generated by the friction torque, and is added to the thrust Fm to press the synchronizer ring 24. This can reduce operating force by an amount of the thrust Fm than that of a shift device without a self-servo function.

[0037] Angles of the chamfers 24c and 24d of the synchronizer ring 24 are set properly so that the thrust pieces 26 can be prevented from moving forward in the axial direction by the synchronizer ring 24 as long as the rotational speed difference is generated between the synchronizer ring 24 and the third gear 18. Therefore, the thrust pieces 26 cannot move to the splines 18a of the third gear 18, and keep pressing the synchronizer ring 24 to function the self-servo operation, adding the self-servo thrust Ft.

[0038] This self-servo operation gradually decreases the rotational speed difference between the synchronizer ring 24 and the third gear 18 into substantially zero, namely diminishing the friction torque into substantially zero. The thrust pieces 26 rotate the synchronizer ring 24 relatively thereto toward its neutral position by the first slanted surfaces 26l, thereby being allowed to move forward toward the third gear 18.

[0039] Then the first slanted surfaces 26l of the thrust pieces 26 move over the chamfers 24d of the synchronizer ring 24, and the projections 24i of the synchronizer ring 24 are received in the recesses 26t of the thrust pieces 26 as shown in FIGS. 18 and 19. In this state, third-gear side portions of the thrust pieces 26 are moved inwardly in the radial direction, and the projections 22g of the sleeve 22 and the recess portions 26d of the thrust pieces 26 are disengaged from each other as shown in FIG. 19, which enables the sleeve 22 to move toward the third gear 18.

[0040] Then the sleeve 22 moves further forward for its splines 22a to engage with the splines 18a of the third gear 18 which are rotating at the substantially same speed as that of the sleeve 22. This engagement brings the end of the shift operation. In this state, the projections 22h of the sleeve 22 contact with the engageable slanted surfaces 26b of the thrust pieces 26 as shown in FIG. 20. The thrust pieces 26 are restricted from being moved toward the hub 12 by the sleeve 22, which ensures to prevent unexpected occurrence in which the thrust pieces 26 move toward the fourth gear 20 in a state where the sleeve 22 engages with the third gear 18.

[0041] A shift operation to the fourth speed is similar to that to the third speed, although movements of the parts are symmetric to those in the shift operation to the third speed.

[0042] The shift device of the embodiment has the following advantages.

[0043] In the shift device of the embodiment, in order to obtain a certain synchronizing capacity, corresponding to friction torque, press force necessary for the sleeve 24 is smaller than that necessary for a shift device with a normal Borg-Warner type synchronizer. This means that the shift device of the embodiment can improve its synchronizing ability.

[0044] In addition, the hub 12 needs only the slanted surfaces 12g to 12j formed on the cut-off portions 12f thereof in the axial direction, and accordingly can be produced by using a sintering process, a sinter forging process, or the like. The reason being that the thrust pieces 26 are formed to have the first slanted surfaces 26k to 26n and the second slanted surfaces 26o to 26r at their four corners so that the thrust pieces 26 are engaged with the sleeve 22 during a synchronizing operation and they are disengaged from each other before the sleeve 22 is engaged with the speed gear after the synchronizing operation. Therefore, the shift device of the embodiment can decrease manufacturing costs of the hub 12.

[0045] While there have been particularly shown and described with reference to preferred embodiments thereof, it will be understood that various modifications may be made therein.

[0046] In the embodiment, the shift device with the synchronizer is mounted on the input shaft 10, but it may be mounted on an output shaft.

[0047] The slanted surfaces 12g to 12j of the hub 12 and the slanted surfaces 26k to 26r of the thrust pieces 26 may be formed in a tapered surface, a helical surface, and others.

[0048] The synchronizer ring 24 may have an oil groove on its inner friction surface in order to increase a friction coefficient of the friction surface, and may be made of material for improving synchronizing ability.

[0049] The shift device with the synchronizer may be applied to a multi-cone type synchronizer, which has several friction surfaces.

[0050] The shift device may be manually operated, or mechanically operated by an actuator.

[0051] The speed gear employs the third gear 18 and the fourth gear 20 in the embodiment, but may be other speed gear.

Claims

1. A shift device with a synchronizer adapted for a transmission comprising:

a shaft (10) for transmitting drive power;

a hub (12) having a boss portion (12b) splined with the shaft (10), a ring portion (12d) located outwardly away from the boss portion (12b) and formed on an outer peripheral surface thereof with splines (12e), and a flange portion (12e) connecting the boss portion (12b) and the ring portion (12d), the ring portion (12d) and the flange portion (12c) being formed with a plurality of notch portions (12f) having axial four edges, and the axial four edges being respectively provided with slanted surfaces (12g to 12j) for changing rotational force to thrust;

a sleeve (22) provided with splines (22a) on an inner peripheral surface thereof and formed with projections (22g) on a part of the splines (22a) of the sleeve (22), the sleeve (22) being supported by and slidable along the spline (12e) of the hub (12);

a pair of speed gears (18, 20) arranged to sandwich the hub (12), the gears (18, 20) having splines (18a, 20a), which are engageable with the splines (22a) of the sleeve (22), and a friction surface (18b, 20b) at a hub (12) side;

a pair of synchronizer rings (24) respectively arranged between the hub (12) and the speed gears (18, 20), the synchronizer rings (24) each having a friction surface (24a) and chamfers (24c, 24d) on an outer circumference thereof, and the friction surfaces (24a) being respectively pressable on the friction surfaces (18a, 20a) of the speed gears (18, 20);

thrust pieces (26) that are movable in the notch portions (12f) of the hub (12) in an axial direction of the shift device; and

a spring which is inserted in each of the notch portions (12f), the shift device characterized in that

the thrust pieces (26) are respectively engageable with the projections (22g) of the sleeve (22), in that

the thrust pieces (26) are formed with first slanted surfaces (26k to 26n) pressable on the chamfers (24c, 24d) of the synchronizer rings (24) and second slanted surfaces (26o to 26r) contactable with the slanted surfaces (12g to 12j) of the hub (12) so that the thrust pieces (26) can change rotational force due to friction torque generated between the friction surfaces (18b, 24a; 20b, 24a) to thrust, in that

each of the thrust pieces (26) is formed with a conical hole portion (26f) at an inner side thereof, in that

a ball (30) is pushed outwardly in a radial direction by the spring (28) to be received in each of the conical hole portion (26f), the ball (30) being contactable with a rear surface (241) of the synchronizer ring (24), pressing the synchronizer ring (24) toward the speed gear (18; 20) to be engaged with force corresponding to tension of the spring (28), and in that

the thrust pieces (26) engage and move together with the sleeve (22) in the axial direction when the sleeve (22) is moved toward the speed gear (18; 20) to be engaged and the first slanted surfaces (26k to 26n) of the thrust pieces (26) press the chamfers (24c, 24d) of the synchronizer ring (24), and the thrust pieces (26) are disengaged from the sleeve (22) when the friction torque becomes zero and the splines (22a) of the sleeve (22) are engaged with the splines (18a; 20a) of the speed gear (18; 20).

2. The shift device according to claim 1, wherein
the synchronizer rings (24) are provided with projections (24j) on outer peripheral surfaces thereof, and
the thrust pieces (26) are formed like a rectangular shape, seen from an outside of the hub (12) in a radial direction, and the thrust pieces (26) being provided with projections (26g to 26j) at four corners thereof, recess portions (26d) engageable with the projections (22g) of the sleeve (22) and formed on outer peripheral surfaces of the thrust pieces (26), and recesses (26t) formed at both end portions of the thrust pieces (26) in the axial direction on inner peripheral surfaces of the thrust pieces (26) for receiving the projections (24j) of the synchronizer rings (24), and wherein
the inner peripheral surfaces of the thrust pieces (26) contact with the projections (24j) of the synchronizer ring (24) when the first slanted surfaces (26k to 26n) press the chamfers (24c, 24d) of the synchronizer ring (24), and the recess portions (26d) of the thrust pieces (26) are disengaged from the projections (22g) of the sleeve (22), receiving the projections (24j) of the synchronizer ring (24) in the recess (26t) of the thrust pieces (26) before the splines (22a) of the sleeve (22) are engaged with the splines (18a; 20a) of the speed gear (18; 20).

3. The shift device according to either claim 1 or claim 2, wherein
the second slanted surfaces (26o to 26r) of the thrust pieces (26) are in a contact-free relationship with the slanted surfaces (12g to 12j) of the hub (12) when the sleeve (22) is placed at a neutral position, and only the second slanted surfaces (26o to 26r) at the to-be-engaged-with speed gear (18; 20) side are contactable with the slanted surfaces (12g to 12j) of the hub (12) when the sleeve (22) is moved toward the to-be-engaged-with speed gear (18; 20).

4. The shift device according to any one of claims 1 to 3, wherein
the springs (28) are disposed in the radial direction between the balls (30) and bottoms of the notch portions (12f), respectively.

5. The shift device according to any one of claims 1 to 4, wherein
the sleeve (22) has projecting portions (22h) at central portions of a part of the splines (22a) thereof, and wherein
the projecting portions (22h) of the sleeve (22) are contactable with the first slanted surfaces (26k to 26n) of the thrust pieces (26) when the splines (22a) of the sleeve (22) are engaged with the splines (18a; 20a) of the speed gear (18; 20).

Ansprüche

1. Schaltvorrichtung mit einem Synchronisator für ein Getriebe, umfassend:

eine Welle (10) zum Übertragen einer Antriebskraft,

eine Nabe (12), die einen mit der Welle (10) verzahnten Ansatzabschnitt (12b), einen Ringabschnitt (12d), der außerhalb entfernt von dem Ansatzabschnitt (12b) angeordnet ist und eine äußere Umfangsfläche davon mit Keilen (12e) bildet, und einen Flanschabschnitt (12c) aufweist, der den Ansatzabschnitt (12b) und den Ringabschnitt (12d) verbindet, wobei der Ringabschnitt (12d) und der Flanschabschnitt (12c) mit mehreren eingekerbten Abschnitten (12f) mit vier axialen Kanten ausgebildet sind, und wobei die vier axialen Kanten jeweils mit abgeschrägten Flächen (12g bis 12j) zum Transformieren von Rotationskraft in Schubkraft versehen sind,

eine Muffe (22), die an einer inneren Umfangsfläche davon mit Keilen (22a) versehen ist und die mit Vorsprüngen (22g) auf einem Teil der Keile (22a) der Muffe (22) ausgebildet ist, wobei die Muffe (22) durch den Keil (12e) der Nabe (12) gestützt wird und daran entlang verschiebbar ist,

ein Paar Getriebezahnräder (18, 20), die so angeordnet sind, daß sie die Nabe (12) zwischen sich einschließen, wobei die Zahnräder (18, 20) Keile (18a, 20a), welche mit den Keilen (22a) der Muffe (22) in Eingriff bringbar sind, und eine Reibungsfläche (18b, 20b) an einer Nabenseiten (12) aufweisen,

ein Paar Synchronisierringe (24), die jeweils zwischen der Nabe (12) und den Getriebezahnrädern (18, 20) angeordnet sind, wobei jeder Synchronisierring (24) eine Reibungsfläche (24a) und Abfasungen (24c, 24d) an einem äußeren Umfang davon aufweist und wobei die Reibungsflächen (24a) jeweils an die Reibungsflächen (18a, 20a) der Getriebezahnräder (18, 20) anpreßbar sind,

Druckstücke (26), die in den eingekerbten Abschnitten (12f) der Nabe (12) in einer axialen Richtung der Schaltvorrichtung bewegbar sind, und

eine Feder, welche in jedem der eingekerbten Abschnitte (12f) eingefügt ist, wobei die Schaltvorrichtung dadurch gekennzeichnet ist,

daß die Druckstücke (26) jeweils mit den Vorsprüngen (22g) der Muffe (22) in Eingriff bringbar sind,

daß die Druckstücke (26) mit ersten abgeschrägten Flächen (26k bis 26n), die an die Abfasungen (24c, 24d) der Synchronisierringe (24) anpreßbar sind, und zweiten abgeschrägten Flächen (26o bis 26r) ausgebildet sind, die mit den abgeschrägten Flächen (12g bis 12j) der Nabe (12) so in Kontakt bringbar sind, daß die Druckstücke (26) die Rotationskraft infolge des zwischen den Reibungsflächen (18b, 24a; 20b, 24a) erzeugten Reibungsmoments in Schubkraft umsetzen können,

daß jedes der Druckstücke (26) mit einem konischen Lochabschnitt (26f) an einer Innenseite davon ausgebildet ist,

daß eine Kugel (30) in einer radialen Richtung durch die Feder (28) nach außen gedrückt wird, um in jedem der konischen Lochabschnitte (26f) aufgenommen zu werden, wobei die Kugel (30) mit einer Rückseite (24l) des Synchronisierrings (24) in Kontakt bringbar ist, wobei sie den Synchronisierring (24) in Richtung des Getriebezahnrads (18; 20) drückt, um mit einer Kraft entsprechend der Spannung der Feder (28) in Eingriff gebracht zu werden, und

daß die Druckstücke (26) mit der Muffe (22) in Eingriff stehen und sich mit ihr zusammen in der axialen Richtung bewegen, wenn die Muffe (22) in Richtung des Getriebezahnrades (18; 20) bewegt wird, um in Eingriff gebracht zu werden, und die ersten abgeschrägten Flächen (26k bis 26n) der Druckstücke (26) die Abfasungen (24c, 24d) des Synchronisierringes (24) anpressen und die Druckstücke (26) von der Muffe (22) ausgeklinkt sind, wenn das Reibungsmoment null wird und die Keile (22a) der Muffe (22) mit den Keilen (18a; 20a) des Getriebezahnrades (18; 20) in Eingriff stehen.

2. Schaltvorrichtung nach Anspruch 1, wobei
die Synchronisierringe (24) mit Vorsprüngen (24j) an äußeren Umfangsflächen davon versehen sind und
die Druckstücke (26) von einer Außenseite der Nabe (12) in einer radialen Richtung aus gesehen wie eine rechteckige Form ausgebildet sind und wobei die Druckstücke (26) mit Vorsprüngen (26g bis 26j) an vier Ecken davon, mit Vertiefungsabschnitten (26d), die mit den Vorsprüngen (22g) der Muffe (22) in Eingriff bringbar und an äußeren Umfangsflächen der Druckstücke (26) ausgebildet sind, und Vertiefungen (26t) versehen sind, die an beiden Endabschnitten der Druckstücke (26) in der axialen Richtung auf den inneren Umfangsflächen der Druckstücke (26) zum Aufnehmen der Vorsprünge (24j) der Synchronisierringe (24) ausgebildet sind, und wobei
die inneren Umfangsflächen der Druckstücke (26) mit den Vorsprüngen (24j) des Synchronisierringes (24) in Kontakt stehen, wenn die ersten abgeschrägten Flächen (26k bis 26n) die Abfasungen (24c, 24d) des Synchronisierringes (24) anpressen, und die Vertiefungsabschnitte (26d) der Druckstücke (26) von den Vorsprüngen (22g) der Muffe (22) ausgeklinkt sind, die die Vorsprüngen (24j) des Synchronisierringes (24) in der Vertiefung (26t) der Druckstücke (26) aufnimmt, bevor die Keile (22a) der Muffe (22) mit den Keilen (18a; 20a) des Getriebezahnrades (18; 20) in Eingriff gebracht werden.

3. Schaltvorrichtung nach Anspruch 1 oder 2, wobei
die zweiten abgeschrägten Flächen (26o bis 26r) der Druckstücke (26) mit den abgeschrägten Flächen (12g bis 12j) der Nabe (12) in einer kontaktfreien Beziehung stehen, wenn die Muffe (22) an einer neutralen Position angeordnet ist, und nur die zweiten abgeschrägten Flächen (26o bis 26r) an der mit dem Getriebezahnrad (18; 20) in Eingriff bringbaren Seite mit den abgeschrägten Flächen (12g bis 12j) der Nabe (12) in Kontakt bringbar sind, wenn die Muffe (22) in Richtung der mit dem Getriebezahnrad (18; 20) in Eingriff bringbaren Seite bewegt wird.

4. Schaltvorrichtung nach einem der Ansprüche 1 bis 3, wobei
die Federn (28) jeweils in der radialen Richtung zwischen den Kugeln (30) und den Böden der eingekerbten Abschnitte (12f) angeordnet sind.

5. Schaltvorrichtung nach einem der Ansprüche 1 bis 4, wobei
die Muffe (22) vorspringende Abschnitte (22h) an mittleren Abschnitten von einem Teil der Keile (22a) davon aufweist und wobei
die vorspringenden Abschnitte (22h) der Muffe (22) mit den ersten abgeschrägten Flächen (26k bis 26n) der Druckstücke (26) in Kontakt bringbar sind, wenn die Keile (22a) der Muffe (22) mit den Keilen (18a; 20a) des Getriebezahnrads (18; 20) in Eingriff stehen.

Revendications

1. Dispositif de changement de vitesse avec un synchroniseur adapté pour une transmission, comprenant :

un arbre (10) pour transmettre la puissance d'entraînement ;

un moyeu (12) ayant une partie de bossage (12b) cannelée avec l'arbre (10), une partie annulaire (12d) positionnée vers l'extérieur à distance de la partie de bossage (12b) et formée sur sa surface périphérique externe avec des cannelures (12e), et une partie de bride (12c) raccordant la partie de bossage (12b) et la partie annulaire (12d), la partie annulaire (12d) et la partie de bride (12c) étant formées avec une pluralité de parties d'encoche (12f) ayant quatre bords axiaux, et les quatre bords axiaux étant respectivement prévus avec des surfaces inclinées (12g à 12j) pour transformer la force de rotation en poussée ;

un manchon (22) doté de cannelures (22a) sur sa surface périphérique interne et formé avec des saillies (22g) sur une partie des cannelures (22a) du manchon (22), le manchon (22) étant supporté par et pouvant coulisser le long de la cannelure (12e) du moyeu (12) ;

une paire de pignons de vitesse (18, 20) agencés pour prendre en sandwich le moyeu (12), les pignons (18, 20) ayant des cannelures (18a, 20a), qui peuvent être mise en prise avec les cannelures (22a) du manchon (22), et une surface de friction (18b, 20b) du côté du moyeu (12) ;

une paire de bagues de synchroniseur (24) respectivement agencées entre le moyeu (12) et les pignons de vitesse (18, 20), les bagues de synchroniseur (24) ayant chacune une surface de friction (24a) et des chanfreine (24c, 24d) sur leur circonférence externe, et les surfaces de friction (24a) pouvant être respectivement pressées sur les surfaces de friction (18a, 20a) des pignons de vitesse (18, 20) ;

des pièces de poussée (26) qui sont mobiles dans les partie d`encoche (12f) du moyeu (12) dans une direction axiale du dispositif de changement de vitesse ; et

un ressort qui est inséré dans chacune des parties d'encoche (12f), le dispositif de changement de vitesse étant caractérisé en ce que

les pièces de poussée (26) peuvent être respectivement engagées avec les saillies (22g) du manchon (22), en ce que,

les pièces de poussée (26) sont formées avec des premières surfaces inclinées (26k à 26n) pouvant être pressées sur les chanfreins (24c, 24d) des bagues de synchroniseur (24) et des secondes surfaces inclinées (26o à 26r) pouvant être mises en contact avec les surfaces inclinées (12g à 12j) du moyeu (12) de sorte que les pièces de poussée (26) peuvent transformer la force de rotation due au couple de friction généré entre les surfaces de friction (18b, 24a ; 20b, 24a) en poussée, en ce que

chacune des pièces de poussée (26) est formée avec une partie de trou conique (26f) dans son côté interne, en ce que

une bille (30) est poussée vers l'extérieur dans une direction radiale par le ressort (28) pour être reçue dans chaque partie de trou conique (26f), la bille (30) pouvant être mise en contact avec une surface carrière (241) de la bague de synchroniseur (24), pressant la bague de synchroniseur (24) vers le pignon de vitesse (18 ; 20) à mettre en prise avec une force correspondant à la tension du ressort (28), et en ce que

les pièces de poussés (26) sont engagées et se déplacent conjointement avec le manchon (22) dans la direction axiale lorsque le manchon (22) est déplacé vers le pignon de vitesse (18 ; 20) à mettre en prise et les premières surfaces inclinées (26k à 26n) des pièces de poussée (26) pressent les chanfreins (24c, 24d) de la bague de synchroniseur (24), et les pièces de poussée (26) sont dégagées du manchon (22) lorsque le couple de friction devient nul et que les cannelures (22a) du manchon (22) sont mises en prise avec les cannelures (18a ; 20a) du pignon de vitesse (18 ; 20).

2. Dispositif de changement de vitesse selon la revendication 1, dans lequel
les bagues de synchroniseur (24) sont prévues avec des saillies (24j) sur leurs surfaces périphériques externes, et
les pièces de poussée (26) sont formées avec une forme analogue à un rectangle, lorsqu'observée à partir d'un extérieur du moyeu (12) dans une direction radiale, et les pièces de poussée (26) étant prévues avec des saillies (26g à 26j) au niveau de leurs quatre coins, des parties d'évidement (26d) pouvant être engagées avec les saillies (22g) du manchon (22) et formées sur des surfaces périphériques externes des pièces de poussée (26), et des évidements (26t) formés dans les deux parties d'extrémité des pièces de poussée (26) dans la direction axiale sur des surfaces périphériques internes des pièces de poussée (26) pour recevoir les saillies (24j) des bagues de synchroniseur (24), et dans lequel
les surfaces périphériques internes des pièces de poussée (26) sont en contact avec les saillies (24j) de la bague de synchroniseur (24) lorsque les premières surfaces inclinées (26k à 26n) pressent les chanfreins (24c, 24d) de la bague de synchroniseur (24), et les parties d'évidement (26d) des pièces de poussée (26) sont dégagées des saillies (22g) du manchon (22), recevant les saillies (24j) de la bague de synchroniseur (24) dans l'évidement (26t) des pièces de poussée (26) avant que les cannelures (22a) du manchon (22) ne soient mises en prise avec les cannelures (18a ; 20a) du pignon de vitesse (18 ; 20).

3. Dispositif de changement de vitesse selon la revendication 1 ou la revendications 2, dans lequel
les secondes surfaces inclinées (26o à 26r) des pièces de poussée (26) sont en relation sans contact avec les surfaces inclinées (12g à 12j) du moyeu (12) lorsque le manchon (22) est placé dans une position neutre, et seules les secondes surfaces inclinées (26o à 26r) du côté du pignon de vitesse à mettre en prise (18 ; 20) peuvent être mises en contact avec les surfaces inclinées (12g à 12j) du moyeu (12) lorsque le manchon (22) est déplacé vers le pignon de vitesse à mettre en prise (18 ; 20).

4. Dispositif de changement de vitesse selon l'une quelconque des revendications 1 à 3, dans lequel
les ressorts (28) sont disposés dans la direction radiale entre les billes (30) et les fonds des parties d'encoche (12f), respectivement.

5. Dispositif de changement de vitesse selon l'une quelconque des revendications 1 à 4, dans lequel
le manchon (22) a des parties en saillie (22h) au niveau de parties centrales d'une partie de ses cannelures (22a), et dans lequel
les parties en saillie (22h) du manchon (22) peuvent être mises en contact avec les premières surfaces inclinées (26k à 26n) des pièces de poussée (26) lorsque les cannelures (22a) du manchon (22) sont mises en prise avec les cannelures (18a ; 20a) du pignon de vitesse (18 ; 20).

Drawing